Heat exchange apparatus



Sept. 29, 1936. H ERG A HEAT EXCHANGE APPARATUS Filed Aug. 14, 1935 Iiatented Sept. 1936' UNITED STATES HEAT EXCHANGE APPARATUS Lawrence H.Frltzberg, Hyde Park,

Mass, as-

signor to B. F. Sturtcvant Company, Inc.,

Boston, Mass.

Application August 14, 1935, Serial No. 36,091 4 Claims. (01. 257-262)This invention relates to heat exchange apparatus and relates moreparticularly to the streamlining of heat exchange tubes such as are usedin air conditioning systems for the heating or cooling 5 of air.

In many air conditioning systems, it is desired to obtain the heatexchange effect by forcing the air to be conditioned over heat exchangetubes through which is circulated a cooling or heating medium dependingupon the duty required. In order to obtain the maximum heat transferfrom air to tube or tube to air, as the case may be, it has beencustomary to provide the tubes with a plurality of spaced extendedsurfaces known more generally as fins.

It is desirable especially where the air is moved at high velocities tostream line the heat exchange coils. Streamlining results in a saving infan power due to the elimination of theeddy currents which form to therear with respect to air flow of round tubes and results in a gain inheat transfer due to the fact that the air passes in close confact withthe entire tube surface of stream-lined tubes, there being no shadowarea to their rear as in the case of round tubes.

It has been proposed heretofore to manufacture heat exchange tubes withstream-lined shapes and even to provide extended surface fins withstream-lined outlines around such tubes, but the cost of and thedifiiculties of manufacture of such tubes as well as the difilculty ofproviding a group of such tubes with headers, has prevented theirgeneral use.

According to this invention, a plurality of round-v tubes is providedthroughout their'length with stream-lined air contacting portions by aplurality of spaced extended surface plates or sheets which are commonto the plurality of tubes and which form between themselves stream-lineden- 40 closures for the tubes.

In one embodiment of the invention, a plurality of extended surfacemetal sheets is placed in spaced relationship around a plurality oftubes, the sheets being provided with round openings to receive thetubes. In the sheet around each round opening, a streamlined indentationis made with a depth corresponding to the width between the spacedsheets. When assembled the streamlined indentations provide the roundtubes between the extended surfaces with stream-lined external contours.

An object of the invention is to provide round heat exchange tubes withefficient, inexpensive stream-lined enclosures.

Another object of the invention is to provide a round heat exchange tubewith an extended surface fin which stream-lines a portion of the tube.

Another object of the invention. is to provide a plurality of roundtubes with a plurality of extended surface sheets which providetherebetween 5 stream-lined enclosures for the tubes.

Other objects of the invention will be apparent from the followingdescription taken together with the drawing.

The invention will now be described with refer- 10 ence to the drawingof which:

Fig. 1 is a side view of an assembled heat exchange unit embodying theinvention;

F1Figl. 2 is a sectional view along the lines 2--2of Fig. 3 is asectional view along the lines 3-4 of Fig. 2, and

Fig. 4 is a sectional view similar to Fig. 3 and illustrates a modifiedway of fitting the extended surfaces around the round tubes. 20

The heat exchange unit illustrated by Fig. 1, comprises the pair ofheaders 5 into which the outer ends of the plurality of tubes 6 arefitted.

The heating or cooling medium may enter the upper header 5 through thepipe 1 and after pass- 25 'ing through the tubes 6 into the lower header5,

may be exhausted through the pipe 8. v

As shown by Figs. 2 and 3, the plurality of extended surface sheets 9are placed in spaced relationship longitudinally of the tubes. In theem- 30 bodiment illustrated, each sheet 9 is common to all of the tubes.The sheets 9 are provided with circular openings ID of substantially thesame diameter as the outer diameter of the tubes 6 and the sheets areforced over the tubes in order that 35.

effective contact for heat transfer purposes may be obtained. of course,the sheets l0 could be soldered to or otherwise suitably attached to theI tubes 6.

Each sheet In prior to assembly on the tubes 40 is pressed in the shopto have the indented stream-lined portions H formed around each circularopening for the reception of a round tube, as shown in plan view'by Fig.2, and in section and in profile by Fig. 3. The indented portions 45 IIhave a depth equal to the desired spacing between the extended surfaceswith the result that when the sheets 9 are assembled upon the tubes 6,the indented portions it provide streamlined enclosures around the tubes6, between the 50 sheets 9.

In the embodiment illustrated by Fig. 4, the circular openings in thesheets 9 for the reception of the tubes 6, have around theircircumferences the in-turned portions 8 2 which extend in contact 55with the outer surfaces of the tubes 6, between the sheets 9. In thisway, a greater surface of contact between the tubes 6 and the extendedsurface sheets 8, is provided.

Whereas one or more embodiments of the inventicn have been described forthe purpose of illustration, it should be understood that the inventionis not to be limited to the exact arrangement disclosed as manydepartures will suggest themselves to those skilled in the art afterhaving had access to this disclosure.

What is claimed is:

1. A heat exchangetube assembly comprising a plurality of substantiallyround tubes, and an extended surface metal sheet extending crosswisesaid tubes, said sheet having attached thereto substantiallystream-lined sheet metal enclosures for portions of said tubes.

2. A heat exchange tube assembly comprising I) a plurality ofsubstantially round tubes, and a pair of extended surface sheetsextending crosswise said tubes, one of said sheets having formed asintegral parts thereof thin walled substantially stream lined enclosuresfor the portions of said tubes between it and the other of said sheets.

3. A heat exchange tube assembly comprising a plurality of substantiallyround tubes, and an extended surface sheet extending cross-wise saidtubes, said sheet having formed therein, a plurality of indentedportions forming substantially stream-lined enclosures for portions ofsaid tubes.

4. A heat exchange tube assembly comprising a plurality of substantiallyround tubes, a pair of extended surface sheets extending cross-wise saidtubes, and means comprising portions of one of said sheets formingsubstantially stream-lined thin walled enclosures for said tubes betweensaid sheets.

LAWRENCE H. FRITZBERG.

